The "sudo" is useless here - it does only affect the execution of "cat", not the shell redirection. Either add your regular user to the dialout group like uXe suggested (and drop the "sudo"), or try sudo sh -c "cat chip.bin > /dev/ttyACM0"

Hmm, I really would recommend sticking with the sudo approach, at least as the default approach. Changing permissions or group membership is not very visible, not readily reversible and persists forever - could cause trouble later.